The need for detergent compositions which exhibit not only good cleaning properties, but also good fabric-softening performance, and other fabric care benefits, is well-established in the art.
EP 0 026 529 describes detergent compositions containing smectite-type clays and certain cationic compounds having cleaning and textile softening performance.
The efficiency of cellulolytic enzymes, i.e. cellulases, in terms of textile cleaning and harshness-reducing agent for fabrics has been recognized for some time; GB-A-2,075,028, GB-A-2,095,275 and GB-A-2,094,826, disclose detergent compositions with cellulase for improved cleaning performance; GB-A-1,368,599 discloses the use of cellulase for reducing the harshness of cotton-containing fabrics; U.S. Pat. No. 4,435,307 teaches the use of a cellulolytic enzyme derived from Humicola insolens as well as a fraction thereof, designated ACXI, as a harshness-reducing detergent additive.
EP-A-0 269 168 discloses optimized detergent compositions containing cellulase, which are formulated at a mild alkaline pH range and provide combined fabric cleaning, fabric softening, and fabric care performance. EP-B-0 125 122 discloses a detergent composition which combines cleaning and textile softening performance by using a synergetic mixture of a long-chain tertiary amine and cellulase.
In WO 89109259 have been disclosed cellulase preparations useful for reducing the harshness of cotton-containing fabrics, comprising an endoglucanase component with a high endoase activity and affinity towards cellulose.
The practical exploitation of cellulases has however, been set back by the fact that cellulase preparations such as those disclosed in the above-mentioned prior art documents, are complex mixtures, of which only a certain fraction is effective in the fabric-care context; it was thus difficult to implement cost effective industrial production of cellulase for the detergent industry; and large quantities of such cellulase preparations would need to be applied, in order to obtain the desired effect on fabrics.
Improvements in cellulase production also often have not proven to be sufficiently identifiable in terms of applicability in detergents. Defining a cellulase selection criterium relevant for detergent application of cellulase was made possible by the C14CMC-method disclosed in EP-A-350 098. A minimum of 10% removal of immobilized radioactive labelled carboxymethylcellulose at 25.times.10.sup.-6 % by weight of cellulase protein in the laundry test solution has been found to provide high activity cellulase. A preferred group of cellulase falling under the high activity definition according to the present invention has been disclosed in copending Danish Patent Application No. : 1159/90 filed May 5, 1990. There is disclosed a cellulase preparation consisting essentially of a homogeneous endoglucanase component which is immunoreactive with a monoclonal antibody raised against a partially purified 43 kD cellulase derived from Humicola insolens DM1800.
The finding that this particular endoglucanase component of cellulase is advantageous for the treatment of cellulose-containing materials now permits to produce the cellulase cost-effectively, e.g. by employing recombinant DNA techniques, and allows to apply only a small quantity of the cellulase preparation, and obtain the desired effect on fabrics.
It has surprisingly been found that an improved detergent composition can be formulated which combine superior cleaning and softening performance by using a synergestic mixture of water soluble quaternary ammonium compounds and high active cellulase. Said cellulase having at least 10% CMC removal at 25.times.10.sup.-6 % by weight of cellulase protein in the laundry test solution.
It is another object of the present invention to provide a method for treating fabrics in a washing machine, comprising the utilization of the present detergent compositions, for the main wash cycle.